4S replaced screen, apple logo then black screen. Rest of phone works,

Hey guys,

I have just replaced a screen on a 4S and hit a road block. The phone now switches on, the apple logo flashes up but then the screen goes off, not black.

The phone then continues to boot and can receive phone calls and what not. Usual functionality remains all except that the screen remains black.

The old screen worked it was just cracked. when putting the old screen in the same thing happens which suggest i may have buggered a connection or something. Tried the usual software stuff, hard reset, restored the phone.

Any one dealt with a similar problem or have any advice. Cheers.